This invention relates to a shaft for conveying an article along a path of travel and, more particularly, to a thin walled tubing shaft having a low mass and yet having structural rigidity.
There are numerous applications requiring that paper or some other article be moved along a path by rollers mounted on a rotating shaft. A typical paper transport comprises a solid cylindrical bar having machine flats and retainer grooves and drilled cross holes for locating and securing feed rolls to the shaft surface. Some examples of prior art drive shafts are found in U.S. Pat. Nos. 3,808,658, 3815,380, 4,568,312, and 4,622,022. It would be desirable to reduce the mass of the prior art shaft assemblies thereby reducing the adverse effects of overcoming inertia, lessening power requirements to drive the shaft, and reducing tooling and part costs. Reduction of the shaft mass, however, must be accomplished without sacrificing the structural rigidity required for the shaft to perform its functions.
The present invention realizes these goals by providing a hollow thin wall shaft which has a pair of grooves extending along its length. The grooves are deep enough, and wide enough to impart structural rigidity to the tube. Rollers are aligned along the length and secured in place by such grooves and screws which lock into the grooves. More particularly, the invention is directed towards a shaft assembly adapted to transport objects across a surface thereof, said assembly comprising an elongated thin wall tube; said tube having a pair of diametrically opposed grooves formed along its length, said assembly further comprising at least two roller members rigidly secured at predetermined positions along the shaft, said shaft adapted to be rotatably driven at one end so as to impart rotational motion to said roller members carrying objects thereon to be conveyed in the direction of motion.